#define _CRT_SECURE_NO_WARNINGS 1

class Solution {
public:
    int maxDepth(TreeNode* root)
    {
        if (root == nullptr)
        {
            return 0;
        }

        int left = maxDepth(root->left);
        int right = maxDepth(root->right);

        return left > right ? left + 1 : right + 1;
    }
};